Internal combustion engine



y 27, 1941- K. L. HERRMANN V 2,243,821

INTERNAL COMBUSTION ENGINE Filed Sept. 25, 1940 Patented May 27,1941

- UNITED STATES PATENT OFFICE INTERNAL COMBUSTION ENGINE Karl L. Hermann, South Bend, Ind. Application September 25 1940, Serial No. 358,241

scam (01314-56) This invention relates to internal combustion engines and particularly to those of the barrel type, the principal object being the provision of a new and novel form of pistons and the cam which will reduce the amount of wear heretofore occurring at this point.

The invention relates to what is commonly known as a barrel type of engine, that is, an engine in which the cylinders are arranged with their axes parallel to the shaft and equally angularly arranged about the shaft and with such axes lying in a cylindrical surface concentric connection between the I with the axis of the shaft. The cylinders are arranged in two groups, one group at each end of the engine and each cylinder of each group is arranged in aligned and opposed relation to a corresponding cylinder of the other group and with a double ended-piston associated with each opposed pair of cylinders, the shaft being provided with an axial cam received by the central portion of the pistons and rollers being interposed between the opposite faces of-the cam and the pistons to transmit the thrust between the pistons and the cam.

Objects of the invention include, in an engine of the type described, a roller construction which will take care of any nus-alignment between the engagement between the rim part and the cooperating cam surface.

The above being among the objects of the present invention, the same consists lnycertain novel features of construction and combinations of parts to be hereinafter describedwith reference to the accompanying drawing, and then claimed,

g which the present invention has been adapted;

rollers-and the cam faces and yet will distribute the wear between the rollers and the cam over a desired width of the face of the cam; the provision, in an engine of the type described, of a roller construction which will have line contact with the cam even though the axis of rotation of the roller may not be in strict parallelism with the cooperating face of the cam; the provision, in an engine of the class described, of a roller having a rim part swivelably or universally mounted thereon enabling it to automatically align itself with a corresponding cam surface to provide line contact therewith; the provision, in an engine of the type described, of a roller construction embodying a supporting part and a rim part having a cylindrical periphery for engagement with a face of the cooperating cam, the rim part being mounted for movement on the supporting part whereby to enable line contact to be maintained between the roller and the cam surface; and the provision, in an engine of the type described, of a roller including a supporting part provided with a crowned peripheral surface and an annular rim part received upon the crowned surface and having a limited amount of movement thereon whereby to permit the rim part to shift upon the supporting part to provide line of the rollers shown in Fig. 2 is an enlarged. fragmentary sectional view taken axially through one of the pistons for the engine shown in Fig. 1, and illustrating the associated rollers in operative. position with respect to the associated cam member; r

Fig. 3 is an enlarged, fragmentary view of one .Fig. 2, the rim portion of the roller being shown in section taken axially therethrough; and.

Fig. 4 is a transverse. the line 4-4 of Fig. 2.

The present invention relates to a barrel type engine. As is well understood in the art these engines comprise a rotating shaft about which is grouped a plurality of equally angularly spaced cylinders arranged withthelr axes lying in the sectional view taken on surface of a cylinder concentricwith the shaft.

. The cylinders in the present case, and as is usual,

are arranged in two groups, one at each end of the engine with their open ends opposed to each other and each cylinder oi one group in alignment with one cylinder of the opposite group. Each opposed pair of cylinders receives therein a double ended piston, and a cam fixed to the rotating shaft is received within or by the central portion of each piston. Usually, and as in the case of the present invention, the pistons support rollers which engage the opposite faces of the cam so as to reduce the friction between the piston and the cam when the thrust of the pistons under explosions in the cylinders is exerted upon the cam to induce a rotational effect thereon.

bustion engine, filed May 14, 1937, and serially numbered 142,653. Also, while the rollers may be supported in the pistons in any suitable manner in accordance with the present invention, the preferred method of supporting them is that shown and described in my co-pending applications for Letters Patent of the UnitedStates for improvements in Internal combustion engine, filed October 29, 1938, and serially numbered 237,625, and filed May 6, 1940, and serially numbered 333,519, respectively. Early experiments with this type of engine illustrated the difficulty of so accurately machining the various parts that all of the rollers between the pistons and the cams, when solid and provided with cylindrical peripheral surfaces, will bear against the cam with true line contact. the surfaces of the rollers often being found to be cocked with respect to the engaged face of the cam, resulting in a condition of contact between the roller and the cam destructive to both. To avoid this disadvantage and as disclosed in the last two co-pending applications above referred to, the peripheral surfaces of the rollers were slightly crowned so as to provide, in theory at least, point contact with the faces of the cam intermediate the width of the same. Such crowning of the peripheral surfaces of the rollers satisfactorilyaccomplished the results sought to be obtained, that is elimmating the disadvantages formerly occurring because of a cocked condition between the rollers and the cam. Further experiments have indicated, however, that with this crowned construction above described, the wear between the rollers and the cam is concentrated upon a substantially narrow circular path upon the face of the cam and, due to the high pressures existing between the rollers and the cams at full engine operation,

premature wearing and breaking down of the cam surface sometimes results, and it is the principal object of the present invention to eliminate this further disadvantage.

The disadvantages of the previous constructions are avoided in accordance with the present invention by providing rollers having a rim portion adapted for line contact with the cam member and so constructed and arranged as to enable it to swivel or shift in response to any misalignment between the periphery of the roller and the cooperating cam surface whereby to maintain the desired line contact between them. This modification in the prior constructions permits line contact between the rollers and the cam surfaces to be maintained at all times, thus distributing the wear between them over the entire width of the face of the cam surfaces and thus aids in materially lengthening the life of the cam surfaces.

Referring now to the accompanying drawing, it may be noted that the engine there shown is, except for the feature of the present invention, identical to that shown in my co-pending applications above referred to and reference to which maybe made for greater detail of the construction of such engine if desired. As far as the present invention is concerned it is sufficient to I understand that the engine is provided with a central or power shaft i mounted for rotation within a pair of cylinder blocks indicated generally at [2 which are arranged with their ends in axially abutting relationship and secured together by means of bolts l4. The axially outer ends of the cylinder blocks l2 are each closed by a suitable cylinder head indicated generally at it which supports suitable inlet and/0r exhaust valves such as i 8 controlling the admission of combustible mixture to and the exhaust of burnt gases from the various cylinders of the corresponding block. Suitable valve actuating mechanism'is driven from the shaft ill at each end of the engine and each is normally enclosed by a housing indicated generally at 20 carried by the corresponding cylinder head l8. In the particular construction shown by way of illustration each cylinder block I2 is internally formed to provide six cylinders 22 arranged with their axes in the surface of a cylinder concentric with the axis of the shaft I 0 and equally angularly spaced with respect to each other about the axis of such shaft. The cylinders 22 of one cylinder block 12 are arranged in axial alignment with the corresponding cylinders of the other cylinder block and in each opposed pair of the cylinders 22 a double ended piston indicated generally at 24 is reciprocably received.

As piston 24 employed in the particular engine shown and which is preferable, but not necessary to the practices of the present invention is shown in greater detail, in Fig. 2 from which it will be noted that it includes opposite end portions 26 integrally connected together by means of a central strutv 28 substantially wholly disposed on one side of a diametrical plane passing through the axis of the piston. This strut 28 is centrally slotted as at 30, the central axis of the slot lying in a plane including the axis of the piston 24 and the opposite ends of the slot 30 comprising semi-cylindrical surfaces arranged with their axes perpendicular to the axis of the piston.- A- corresponding semicylindrical surface 32 is formed on the opposite side of the piston in alignment with the semicylindrical surfaces first described and the corresponding piston portions 26 are centrally cut away as at 34 between each aligned pair of semicylindrical surfaces. These semi-cylindrical surfaces form bearing surfaces for the trunnions of the rollers which themselves are received in corresponding pockets 34 and project outwardly toward one another therefrom.

A cam member 33 is fixed to the shaft II on line with the joint between the cylinder blocks l2. The cam member 33 is formed with a rim 40 which is circular in axial view but the axial faces 42 of which curve axially of the'shaft II in a simple harmonic curve to provide a cam surface on each side thereof having two diathe shaft I 0.

metrically opposed axial high points thereon. The width of the rim 40 is such as to be closely received between the rollers received in the opposed pockets 34 of each piston 24, thus constraining each piston to reciprocate in its corresponding cylinders as the rim 40 passes between its corresponding rollers and such rollers acting upon the corresponding faces 42 of the rim 40, under the force of an explosion in one of the corresponding cylinders, to impart a rotational described and shown, the central or supporting portions of the rollers are preferably formed integrally with the trunnions and one trunnion 55 thus projects from each side of each roller when the latter is received in the corresponding pocket 34, the one trunnion being received by the cor-- responding semi-cylindrical bearing surface 32 and the opposite trunnion being received by the corresponding semi-cylindrical bearing surface formed at the corresponding end of the slot 30.

As previously stated, in my first co-pending application above referred to, solid rollers having cylindrical peripheral surfaces were employed but it was found that due to inevitable inaccuracies in manufacture it was substantially impossible, at least from a production standpoint, to construct all of the parts so accurately as to insure constant line contact between the peripheries of the rollers and the cooperating cam surfaces at all times, at least some of the rollers inevitably being cocked to a. greater or lesser extent and resulting in undesirable conditions fostering premature breaking down of the cam surfaces.

I In my second and third co-pending applications above referred to rollers having crowned peripheral surfaces are employed in order to eliminate the undesirable conditions arising because of any cocked nature of any of the rollers with respect to their corresponding cam surfaces. While such crowning of the rollers accomplished the desired purpose, nevertheless it resulted in more or less point contact between the rollers and the cam surfaces which thus limited the contact between the rollers and the cam surfaces to a relatively narrow line on the cam surfaces with consequent increased wear on such narrow line and, while entirely practical and fully commercial, resulted in a breaking down of the cam surfaces in too short a time as compared to the life of other moving parts of the engine. Accordingly, it will be appreciated that tests of these earlier roller constructions indicated the desirability of employing line contact between the rollers and the cam surfaces but the addition of some means to eliminate the effect of any cocked relation be-.

tween the rollers and the cam due to certain deficiencies in manufacturing operations. This desired effect is obtained in accordance with the present invention by constructing the rollers in two parts, one of which.is an annular rim portion having a cylindrical peripheral surface adapted for line contact with the cam, surfaces and the other a supporting part arranged within the rim portion and so constructed and arranged as to permit the rim portion to shift or swivel thereon in order that it may maintain its periphery in line engagement with the cooperating cam surface.

In the particular roller construction shown in the drawing by way of illustration of the present invention each roller is indicated generally at 45 and as being provided with a trunnion 50 projecting from each side thereof. The rollers 45 are of an axial width substantially equal but slightly less than the width or thickness of the supporting part 52 and a rim part 54. In the broader aspects of the present invention the supporting part 52 may be formed separately from and then fixedijlto the trunnions 50, the trunnions 50 may be formed integrally with each other and the supporting part 52 may rotate thereon or, as is preferable and particularly where the piston construction shown is employed, the supporting part 52 may be formed integrally with the trunnions 50 and this is the construction shown. In accordance with the present invention the method of supporting the rim part 54 upon the supportlng'part 52 is such as to permit the rim part 54 to shift or swivel upon the supporting part 52 so as to enable it to have a small amount of universal movement thereon thereby to enable the periphery of the rim part 48, which is preferably cylindrical, to constantly maintain "line contact with the corresponding cam face 42 regardless of any reasonable variation in the desired true parallel relationship between the axes of the rollers and the cooperating cam faces 42. There are, of course, a variety of different ways of constructing this supporting part 52 of the rim 54 to obtain this desired relation between the parts. For instance, the supportingpart 52 may be provided with a peripheral surface forming a portion of the sphere and the inner surface of the rim 54 may be formedto correspond and fit the same, but in such case it will ordinarily be necessary to form the rim portion 54 of more than one piece. On the other hand, it is possible to form the supportingpart 52 with a cylindrical or other circular periphery, and to so curve the inner-peripheral surface of the rim portion 54 as to permit the rim portion to more or less swivelably adjust itself upon the supporting portion 52 to maintain line contact between the periphery of the rim 54 and the corresponding cam face 42. Again, the inner peripheral surface of the rim 54 may be made cylindrical and the periphery of the supporting part 52 may be formed as part of a sphere or otherwise crowned to permit a more or less swiveling shifting movement of the rim 54 thereon to maintain the desired line contact between the rim member 54 and the cooperating cam surface 42. It will also be appreciated that if believed to be desirable or necessary means may be provided to prevent relative rotation between the supporting parts 52 and the rim member 54, such as providing 'keyways or inter-engaging splines between them.

Perhaps the simplest and most economical method of forming the supporting part 52 and the rim portion 54 to obtain the desired result is that illustrated in the drawing and in which the inner periphery of the rim portion 54 is cylindrical and the periphery of the supporting portion 52 is crowned. In the case shown the periphery of the supporting part 52 is not crowned sufficiently to render the periphery a part of a pockets 34 so as to enable them to be partially received in such pockets and be maintained against unnecessary axial -movement therein.

One of the trunnions 50 is received by the corresponding semi-cylindrical bearing surface 32 and the other of the trunnions 50 received in the semi-cylindrical bearing surface formed at the corresponding end of the slot 30 in the strut portion 28 of the corresponding piston 24. The

roller 44 itself is formed in two parts, namely a 7 spherical surface, but rather it is crowned on a curve substantially equal to the maximum diameter of the supporting part 52 as illustrated in Fig. 3. The diameter of the supporting part 52 is such that it has a relatively close but sliding fit in the bore of the rim member 54 so that the rim member 54 may easily adjust itself angularly on the supporting part 52. No means for preventing relatlve rotation between the supporting part 52 and rim portion 54 is employed in the construction shown for the reason that there will be materially less friction between the trunnions 50 and their bearings than between the supporting portion 52 and the rim portion 54 and contion between theseparts exists'and any slight rotational movement will have no 111 efiect in any case. There is no possibility of axial disengagement of the supporting portions 52v and the rim portions 54 of the rollers Qt when assembled in the pistons 24 for the reason that a-portion of both the supportingpor'tion 52 and rim portion 54 of each roller is received within the cooperating pockets 34 of the piston which thus maintains these parts in substantially aligned relation. The width of the pockets 34 is,

, of course, sufilciently greater than the width of the rim portions 54 to permit the desired swiveling action of the rim portion 54 on the supporting portion 52 of each roller but is preferably no greater than necessary to allow the required movement of the rim portions to attain the intended results.

It will be appreciated from the foregoing 'de-' scription that the roller construction provided in accordance with the present invention is such as to maintain line contact between the rollers and the cooperating cam faces regardless of any slightly mls-allgned'relation between the axes of the'rollers and the cam faces and thereby eliminates the disadvantages of my prior constructions in a relatively simple and efficient manner. jj.- v

Formal changes may be madeiin the specific embodiment of; the invention disclosed without departing" from the spirit or substanceof the broad invention,;. the ofwhich .is commensurate with; the appended claims.v I What Iclair'rrf'l'sz. 1,

1. In an en'gine'of".theiclass wherein a group of cylinders. are arranged about each end of a rotatable power shaft with their. axes parallelto is provided with curved cam faces onaxially op posite sides of the rim 1 portion thereof for cosequently very little likelihood of relative rotasaid shaft and each cylinder of each group isaligned with'a'nd opposed to a cylinder of the other group, a double. ended piston is reciprog;

cably received by each opposedpair of cylinders; and an axial cam is fixed to'the power shaft and operative engagement; with the pistons, the combination with said pistons and cam of-aroller rotatably carried by each of said pistons on'each' side of said cam for engagement with the corresponding cam face of said cam,,at least one of said rollers comprising a central supporting por-.

provided with curved cam faces on axially oppo-.

rite sides of the rim portion thereof for cooperative engagement with the pistons, the combination with said pistons and cam of a roller rotatably carried by each of said pistons on each side of said cam for engagement with the corresponding cam face of said cam, said rollers each cornprising-a central supporting portion and a rim portion mounted thereon for a limited amount of movement of its axis angularly with respect to the axis of said supporting portion. r

3. In an engine of the class wherein a grou v of cylinders are arranged about each end of a sov rotatabie'power shaft with their axes parallel to said shaft and each cylinder of each group is aligned with and opposed to a cylinder of the other group, a double ended piston is reciprocal)- ly received by each opposedpair of cylinders,

and an axial cam is fixed to the power shaft and is provided with curved committees on axially opposite sides of the rim portion thereof for cooperative engagement with the pistons, the combination with said pistons and cam of a roller rotatably carried by each of said pistons on each side of said cam for engagement with the corresponding cam face of said cam, said rollers each comprising a central portion and an outer rim portion, said rim portion having a substantially cylindrical outer periphery and being swivelably mounted upon said supporting portion.

4. In an engine of the class wherein a group of cylinders are arranged about each end of a rotatable power shaft with their axes parallel to said shaft and each cylinder of each group is aligned with and opposed to a cylinder of the other group, a double ended piston is reciprocably received by each opposed pair of cylinders, and an axial cam is fixed to the power shaft and is provided with curved cam faces on axially opposite sides of the rim portion thereof for cooperative engagement with the pistons, the combination with said pistons and cm of a roller rotatablycarried by each of said pistons on each side of said cam for engagement with the corresponding cam face of said cam, said rollers each comprising a centralportion having a crowned periphery and a rim portion having a substantially cylindrical outer periphery and swivelably mounted upon the crowned periphery of said supporting portion.

5. In an engine of the class wherein a group ofcylinders are arranged about each end of a rotatable power shaft with their axes parallel to said'shaft and each cylinder of each group 1 is aligned with and opposed to a cylinder of the other'group, a double ended piston is re- "ciprocably received by each o d pair of cylinders, and an axial cam is fixed to the power shaft, and is provided with curved cam faces on axially opposite sides of the rim portion thereof for cooperative engagement with the pistons, the

combination with said pistons and cam of a roller rotatably carried by each of said pistons on each side of said cam for engagement with the corresponding cam face of said cam, said rollers each comprising a central portion having an axially curved peripheral surface and said rim portion having a cylindrical bore slidably received upon the periphery of said supporting portion whereby to enable said rim portion a limited amount of universal movement on said supporting part.

6. In an engine of the class wherein a group of cylinders are arranged about each end of a rotatable, power shaft with their axes parallel to said shaft and each cylinder of each group is aligned with and opposed to a cylinder of the other group, adouble ended piston is re- 'ciprooably received by eacliopposed pair of cylinders, and an axial cam is fixed to the power shaft and is provided with curved cam faces on axially opposite sides of the rim portion thereof for cooperativeengagement with the pistons, the combination with said pistons and cam of a roller'rotatably carried by each of said pistons on each side of said cam for engagement with the corresponding cam face of said cam, said rollers ited amount of universal movement on said suprotatable power shaft with their axesparallel to said shaft and each cylinder of each group is aligned with and opposed to a cylinder of the other group,-'a double ended piston is reciprocably received by each opposed pair of cylinders,

and an axial-cam is fixed to the powershait and is provided with curved cam faces on axially opposite sides of the rim portion thereof for co- J operative engagement with the pistons, the combination with saidpistons and'cam of a roller rotatably carried by each of saidpistonson each i side of said cam for engagement with thercorresponding cam face-of said cam, .saidrollerseach comprising a central portion having an axially curved peripheral surfacegiandsaid rim portion having a cylindrical, bore slidably 're ,ceived upon the peripheryof said supporting portion whereby to enable said ,rim portion a limporting part, and said rim portion being free to slide axially on said supporting portion when otherwise unconfined'and being free to rotate upon said supporting portion.

8. In an engine of the class wherein a group of cylinders are arranged about each end of a rotatable power shaft with their axes parallel to said shaft and each cylinder of each group is aligned with and opposed to a cylinder of the other group, a double ended piston is reciprocably received by each opposed pair of cylinders, and an axial cam is fixed to the power shaft and is provided with curved cam faces .on axially opposite sides of the rim portion thereof for cooperative engagement with the pistons, the combination with said pistons and cam of a roller rctatably carried by "each of said pistons on each side of said cam for engagement with the corresponding cani face of said cam, each of said rollers comprising a central portion and a rim portion, said central portion being axially curved on a radius approximately equal to the maximum diameter of said supporting part, and said rim portion having substantially cylindrica1 inner and outer peripheral surfaces. the inner of which is slidably but closely received upon the periphery of said supporting portion.

KARL L. HERRMANN. 

